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mario2005 5th May 2006 08:19 PM

Schematic needed 811a Class A2
Could you post a schematic for Tube Power Amplifier with 811a Class A2 .
Does someone has some experience using the 811a in SE-A2 mode ?

Does someone have a schematic for Tube Power Amplifier with 811a WAVAC MD-811.



jim 6th May 2006 07:19 AM

Here's a nice collection of 811A amps.

my 811 collection (ZIP-file)


Ryssen 6th May 2006 03:53 PM

Do you hav a collection for 845 SE to?;)

contaxchen 7th May 2006 12:55 AM

THis is a good collection.
why they like to use 6f6 as driver tube? What's the secrect?

jrdmedford 7th May 2006 02:52 AM

Got great results with 811A parafeed
Here's the schematic:

This design is similar to Bob Danielak's 826 amp. It is very cheap to build too
and you can use simple Series Fed output transformers (Edcor, Big Hammonds).
In my case, I turned my Hammond 1628SE into a big plate load choke and used
a Nickle cored parafeed transformer. A bunch of guys listened to this (Karlson horns, Fostex, other stuff) and really loved this - more so than the 845.

This is good for 8-9W. Strong watts too, with tight bass and surreal clarity with the high. The dynamics sparkle.

I'd try it first with AC filaments on the 811A and a humbucking pot. If and only if
hum is too much, then attempt a DC supply for the 811A filaments. A DC supply
for the 811 will be expensive and complex. Rectifying 4A of current with no RF artifacts is going to be tough. You'd need a common mode choke for sure.

-- Jim

jim 7th May 2006 07:55 AM


Originally posted by Ryssen
Do you hav a collection for 845 SE to?;)
Yep, just posted :

845 collection


Ryssen 7th May 2006 08:01 AM

Thank You!:)

ttan98 7th May 2006 09:57 AM

Most helpful Jim!!!!

corbato 7th May 2006 04:01 PM

811A just rocks!
I manage to get away with an AC filament supply. Just about audible hum. Nice light bulb!

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